Process for producing epoxidized diene polymer

ABSTRACT

A process for producing an epoxidized diene polymer includes: dispersing or suspending a diene polymer (C) having a ball-reduced particle size of 0.05-20 mm in a medium (A) in the presence of powder particles (B) insoluble in the medium (A), or in an aqueous medium in the presence of a phenol-based stabilizer and/or a phosphorus-based stabilizer; and epoxidizing the diene polymer (C) by an epoxidizing agent, therefore, problems associated with epoxidation performed by dissolving diene polymer in a solvent are eliminated; an economical method for epoxidizing, producing, and purifying a diene polymer (C) in a solid form is provided; and the epoxidized diene polymer having an excellent heat stability can be obtained.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process for producing an epoxidizeddiene polymer which is used for coatings, resin modifiers, rubbermodifiers, adhesives, and so on. More particularly, the presentinvention relates to a process for producing an epoxidized dienepolymer, in which when performing an epoxidation of a double bond in thediene polymer chain, the diene polymer is dispersed and suspended in aninsoluble medium such as water or the like and is epoxidized in thepresence of powder particles insoluble in the medium or in the presenceof both the powder particles and a thermo-stabilizer, to thereby obtainthe epoxidized diene polymers with a low gel content and/or with anexcellent thermal stability.

2. Description of the Related Art

Heretofore, as a process for producing an epoxidized diene polymer bythe oxidization of a diene polymer to be epoxidized, the followingmethods have been known in the art:

(i) a method in which a percarboxylic acid is previously prepared as anepoxidation agent by reacting hydrogen peroxide with a lower carboxylicacid such as formic acid or acetic acid, and the percarboxylic acid isthen added in a reaction system to initiate an epoxidation reaction inthe presence or absence of a solvent; and

(ii) a method in which an epoxidation is performed using hydrogenperoxide in the presence of a catalyst such as osmium salt or tungsticacid and a solvent.

Each of the methods (i) and (ii) is characterized by dissolving a dienepolymer to be epoxidized in a solvent to effectively execute anepoxidation reaction. However, there is a disadvantage in that therecovery of products is extremely troublesome because of complicatedsteps of dissolving the diene polymer to be epoxidized in the solvent,and performing a washing treatment with water to eliminate by-productssuch as carboxylic acids and desolvation operation. In particular, whenthe organic polymer to be epoxidized is a rubber polymer, there is aproblem in that the epoxidized products have adhesive properties. Thatis, the adhesive properties of such products will cause blocking of theproducts just after production, difficulty in handling, workabilitybeing changed for the worse, blocking at the time of storing theproducts, and so on.

Furthermore, depending on the product form, a usage mode is limited.When the product is used as a modifying agent, it may become a bale formin which the product cannot be manufactured as powder, clam, pellet, orthe like after denaturing by epoxidation.

Regarding the process for producing an epoxidized diene polymer, thepresent inventors and coworkers have provided many proposals. InJP-A-08-120022, for example, there is proposed a method comprising thefollowing steps: (1) mixing a diene polymer and/or partiallyhydrogenated product thereof with an organic solvent to obtain anorganic solvent slurry or an organic solution of the diene polymer; (2)epoxidizing a double bond in the diene polymer using an epoxidationagent; (3) neutralizing and/or washing the epoxidation-reactionsolution; (4) stripping a solution with 5 to 50 wt % of the epoxidizedblock copolymer in the presence of a surfactant at a temperature equalto or higher than the boiling point of the organic solvent, or at anazeotropic temperature or higher if the organic solvent and water forman azeotropic mixture, but not higher than 120° C. to obtain a slurry inwhich the epoxidized block copolymer is dispersed in water; (5)dehydrating the clam of epoxidized block copolymer containing waterobtained in the previous step to a water content of 1 to 30 wt %; and(6) drying the epoxidized block copolymer obtained in the previous stepto a water content of 1 wt % or less.

In JP-A-09-60479, there is proposed a method in which a screw-extrudertype throttle dehydrator is used in the above drying step (6). InJP-A-09-95512, there is proposed a method for recovering epoxidizedblock copolymer, in which an organic solvent is removed through a directvaporization by supplying the epoxidized block copolymer obtained in theabove step (3) into a vaporizer. Further, in JP-08-104709, there isproposed a process for producing an epoxidized block copolymer having animproved gel content by specifying an acid number of a product.

However, each of these methods of the inventions relates to theepoxydized block copolymer in accordance with a uniform solution methodfor the epoxidation after dissolving the polymer (raw material) in thesolvent, which is characterized by producing the product having a lowgel content. The handling of high viscosity solution is full ofdifficulty. Furthermore, epoxidized block copolymers obtained by thosemethods have comparatively low softening points, respectively.Therefore, during the production, processing, transportation, or usageof such polymers, any trouble maybe caused in handling. For example, thepellets of the copolymer become blocked on their surfaces with eachother or strongly adhered with each other.

As a method to cope with the problems, JP-A-09-67502 proposes onecharacterized by the addition of a blocking-preventing agent to theobtained epoxidized copolymer.

In JP-A-09-208617, there is proposed a chemically modified diene polymercomposition and a preparation method therefor, where the polymer in theform of micro particles having a size of 0.05 to 10 ìm in water isdenatured with epoxidation. However, it only discloses the process forproducing the composition, so that there is no description about therecovery of epoxidized polymer, the improvement on blocking of theproduct, or the like. In JP-A-10-298232, furthermore, there is proposeda method for the epoxidation in an aqueous dispersion. However, themethod is provided for specifically epoxidizing only the surface ofpolymer particle. Both applications do not mention about the heatstability of the obtained epoxy chemical product alone.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above, and an objectof the present invention I is to provide a process for producing aparticulate epoxidized diene polymer, where a diene polymer is denaturedwith epoxidation to obtain an epoxidized diene polymer which can be usedas a modifier or the like for typical synthetic resins or one ofcomponents that make up synthetic resin compositions, while overcomingthe conventional problems to be caused in the conventional epoxydenaturation method, for example, a method in which the epoxydenaturation is performed by dissolving the diene polymer in a solvent,and the conventional epoxy denatured compound, where the problemsinclude, for example, troublesome in the handling of the compound to becaused by the properties of adhesiveness generally included therein.

An object of the present invention II is to provide a method forcost-effectively producing an epoxidized diene copolymer with excellentheat stability.

As the present inventors have enthusiastically studied for attaining theobject of the present invention I, the present inventors have finallyaccomplished the present invention I by finding a process for producinga polymer with a low gel content by performing in the presence of powderparticle the epoxidation in the solvent where the polymer cannot bedissolved, in the epoxidation reaction step. Such a method solves theproblems such as the blocking or adhesive properties of the product.Concretely, the present inventors have found a process for producing anepoxidized diene polymer with low gel content, which is the finalproduct in a state of without being blocked, by the steps of: proceedingan epoxidation reaction in the medium without causing blocking in thepresence of an insoluble medium and powder particles, where theepoxidation of diene polymer is performed using peracetic acid and areaction accelerator in a system where the diene polymer is dispersed orsuspended as a solid form such as pellets or powders; and drying theproduct while keeping its epoxidized form.

As the present inventors have enthusiastically studied for attaining theobject of the present invention II, the present inventors have finallyaccomplished the present invention II by finding a process for producinga polymer with an excellent heat stability by performing the epoxidationin a water dispersion system in the presence of a heat stabilizer.Concretely, the present inventors have found a process for producing anepoxidized diene polymer with an excellent heat stability, by the stepsof: performing the epoxidation of diene polymer in an aqueous solventusing peracetic acid and a reaction accelerator, in a system where thediene polymer is dispersed or suspended as a solid form such as pelletsor powders in the presence of a phenol-based stabilizer and/or aphosphorus-based stabilizer and powder particles; and separating andrecovering the product in a solid form, followed by removing the solventfrom the product.

Therefore, according to a first aspect of the present invention, thereis provided a process for producing an epoxidized diene polymer, themethod comprising: dispersing or suspending a diene polymer (C) in amedium (A) in the presence of powder particles (B) insoluble in themedium (A); and epoxidizing a double bound of the diene polymer (C) byan epoxidizing agent in the presence of an optionally added phenol-basedstabilizer and/or an optionally added phosphorus-based stabilizer.

According to a second aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer, the methodcomprising: dispersing or suspending a diene polymer (C) in an aqueousmedium in the presence of a phenol-based stabilizer and/or anphosphorus-based stabilizer; and epoxidizing the diene polymer (C) by anepoxidizing agent in the presence of powder particles (B) insoluble in amedium which is optionally added.

According to a third aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in theabove-mentioned first aspect, in which the medium (A) is an inert mediumthat does not dissolve the diene polymer.

According to a fourth aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in theabove-mentioned third aspect, in which the medium (A) is water.

According to a fifth aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in theabove-mentioned first or second aspect, in which the powder particles(B) are inorganic particles and/or organic-inorganic complex particles.

According to a sixth aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in theabove-mentioned fifth aspect, in which the inorganic particles are talcand/or silica.

According to a seventh aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in theabove-mentioned first or second aspect, in which the total usage amountof the phenol-based stabilizer and/or phosphorus-based stabilizer is0.05-5 parts by weight with respect to 100 parts by weight of the dienepolymer.

According to an eighth aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer (C) as described inthe above-mentioned first or second aspect, in which the diene polymer(C) is at least one selected from the group consisting of: butadienepolymer, styrene/butadiene copolymer, isoprene polymer, styrene/isoprenecopolymer, acrylonitrile/butadiene copolymer, and partial hydridesthereof.

According to a ninth aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in theabove-mentioned eighth aspect, in which the diene polymer has aball-reduced particle size in the range of 0.05 to 20 mm.

According to a tenth aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in theabove-mentioned first or second aspect, in which the epoxidizing agentis peracetic acid, or the other percarboxylic acid which can be inducedusing hydrogen peroxide.

According to an eleventh aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in anyone of the above-mentioned first to tenth aspects, a solvent foraccelerating an epoxidizing reaction is used at the time of theepoxidizing reaction.

According to a twelfth aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in theabove-mentioned eleventh aspect, the solvent for accelerating theepoxidizing reaction is an organic solvent having an SP (solubilityparameter) value of 10 or less.

According to a thirteenth aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in theabove-mentioned twelfth aspect, the solvent for accelerating theepoxidizing reaction is at least one selected from the group consistingof: cyclohexane, toluene, xylene, ethyl acetate, tetrahydrofuran,benzene, methyl ethyl ketone, and chloroform.

According to a fourteenth aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in theabove-mentioned first or second aspect, the epoxidized diene polymer hasan oxirane oxygen concentration of 0.3-5.0% by weight.

According to a fifteenth aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in theabove-mentioned first or second aspect, in which the epoxidizingreaction of the diene polymer is performed at a temperature of 10-70° C.

According to a sixteenth aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in theabove-mentioned first or second aspect, the method comprising: a firststep in which the diene polymer (C) is epoxidized in the medium in thepresence of an epoxidizing agent or in the presence of both anepoxidizing agent and a solvent for accelerating an epoxidizingreaction; a second step in which the epoxidized diene polymer is washedwith water, or the epoxidized diene polymer is neutralized and washedwith water; and a third step in which the solvent for accelerating theepoxidizing reaction used in the first step is removed, where the thirdstep is an optional step to be provided as necessary.

According to a seventeenth aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in theabove-mentioned sixteenth aspect, in which the second step includes anoperation for a solid-liquid separation to separate the epoxidized dienepolymer that is to be supplied to the third step.

According to an eighteenth aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in theabove-mentioned sixteenth aspect, in which the removal of the solvent inthe third step includes drying the epoxidized diene polymer obtainedfrom the second step, while keeping the particle form of the epoxidizeddiene polymer.

According to a nineteenth aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in theabove-mentioned eighteenth aspect, in which the removal of the solventin the third step is performed by a kneading-type evaporator.

According to a twentieth aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in anyone of the above-mentioned first to nineteenth aspects, in which theresulting epoxidized diene polymer has a gel content of not more than 2%by weight.

According to a twenty-first aspect of the invention, there is provided aprocess for producing an epoxidized diene polymer as described in anyone of the above-mentioned first to nineteenth aspects, in which the gelcontent of the epoxidized diene polymer after heating it in an oven for30 minutes at a temperature of 180° C. (in air) is less than 2.5 timesof the gel content of the epoxidized diene polymer before the heating.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, we will describe preferred embodiments of the presentinventions I and II.

In the present inventions I and II, diene polymers (C) which can be usedas raw materials of the epoxidation include polymers of butadiene alone,copolymers of butadiene and other monomers, polymers of isoprene alone,or copolymers of isoprene and other monomers.

As the other monomers to be copolymerized with butadiene or isopreneinclude, for example, the other conjugated dienes, vinyl compounds, andthe like.

The other conjugated dienes to be copolymerized with butadiene include,for example, isoprene, 1,3-pentadiene (also referred to as piperylene),2,3-dimethyl-1,3-butadiene, 3-butyl-1,3-octadiene, andphenyl-1,3-butadiene. Each of these other conjugated dienes can be usedalone or they can be used as a combination of two or more members.

In addition, the other conjugated diene to be copolymerized withisoprene include, for example, butadiene, 1,3-pentadiene,2,3-dimethyl-1,3-butadiene, 3-butyl-1,3-octadiene, andphenyl-1,3-butadiene. Among them, butadiene and isoprene are preferable.Each of these other conjugated dienes can be used alone or they can beused as a combination of two or more members.

Furthermore, vinyl compounds to be copolymerized with butadiene orisoprene include, for example, alkyl-substituted styrenes such asstyrene, á-methylstyrene, o-methylstyrene, m-methylstyrene,p-methylstyrene, and p-tert-butylstyrene; alkoxy-substituted styrenessuch as o-methoxystyrene, m-methoxystyrene, and p-methoxystyrene; vinylaromatic compounds such as divinylbenzene, and 1,1-diphenylstyrene;unsaturated monocarboxylate esters such as methyl (meta)acrylate, ethyl(meta)acrylate, n-propyl (meta)acrylate, i-propyl (meta)acrylate,n-butyl (meta)acrylate, i-butyl (meta)acrylate, sec-butyl(meta)acrylate, t-butyl (meta)acrylate, lauryl (meta)acrylate, methylcrotonate, ethyl crotonate, methyl cinnamate, and ethyl cinnamate;fluoroalkyl (meta)acrylates such as 2,2,2-trifluoroethyl (meta)acrylate,2,2,3,3,3-pentafluoropropyl (meta)acrylate, and2,2,3,3,4,4,4-heptafluorobutyl (meta)acrylate; (meta)acryloyl groupcontaining siloxanyl compounds such as 3-(trimethylsiloxanyldimethylsilyl)propyl (meta)acrylate,3-[tris(trimethylsiloxanyl)silyl]propyl (meta)acrylate, anddi-[3-(meta)acryloylpropyl]dimetylsilyl ether; mono- ordi-(meta)acrylates of alkyleneglycol such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, and 1,6-hexanediol; alkoxyalkyl(meta)acrylates such as 2-methoxyethyl (meta)acrylate, 2-ethoxyethyl(meta)acrylate, 3-methoxypropyl (meta)acrylate, and 3-ethoxypropyl(meta)acrylate; cyanoalkyl (meta) acrylates such as 2-cyanoethyl(meta)acrylate and 3-cyanopropyl (meta)acrylate; oligo (meta)acrylatessuch as di-, tri-, or tetra (meta)acrylates of at least trivalentpolyhydric alcohols such as glycerin, 1,2,4-butanetriol,pentaerythritol, and trimethylolalkane (the number of carbons in alkaneis, for example, 1 to 3); cyanated vinyl compounds such as(meta)acrylonitrile, á-chloroacrylonitrile, and cyanatedvinylidene;unsaturated amides such as (meta)acrylamide, N-methylol(meta)acrylamide, N,N′-methylene bis(meta)acrylamide, and N,N′-ethylenebis(meta) acrylamide; hydroxyalkyl (meta)acrylates such as2-hydoroxyethyl (meta) acrylate, and 2-hydroxypropyl (meta)acrylate;hydroxyalkyl esters of unsaturated monocarboxylic acids, such as2-hydroxyethyl crotonate, 2-hydroxypropyl crotonate, 2-hydroxyethylcinnamate, and 2-hydroxypropyl cinnamate; unsaturated alcohols such as(meta)allyl alcohol; unsaturated monocarboxylic acids such as (meta)acrylic acid, crotonic acid, and cinnamic acid; unsaturatedpolycarboxylicacids(anhydrides)such as; (anhydrous) maleic acid, fumaricacid, (anhydrous) itaconic acid, and citraconic acid; mono- or di-estersof the unsaturated polycarboxylic acids described above; unsaturatedcompounds containing epoxy groups such as (meta)allylglycidyl ether, andglycidyl (meta)acylate; and vinyl chloride, vinyl acetate, sodiumisoprene sulfonate, di-cyclopentadiene, and ethylidene norbornene.

Among them, styrene-based vinyl compounds are preferable. Each of thesevinyl compounds can be used alone or they can be used as a combinationof two or more members.

In the present inventions I and II, butadiene copolymers and isoprenecopolymers may be random copolymers or block copolymers.

Polymers to be epoxidized preferably include polymers of butadienealone, random copolymers of butadiene and styrene, random copolymers ofbutadiene and (meta)acrylonitrile, block copolymers of butadiene andstyrene, random copolymers of isoprene and styrene, random copolymers ofisoprene and (meta)acrylonitrile, block copolymers of isoprene andstyrene, and copolymers of butadiene and isoprene. In some cases, thecopolymers of buta diene and isoprene may include vinyl compounds suchas styrene and (meta) acrylonitrile.

A butadiene content ratio in the butadiene copolymers or an isoprenecontent ratio in the isoprene copolymers is 0.5-99.5% by weight ingeneral, preferably 1-95% by weight, more preferably 5-90% by weight.

In the copolymers of butadiene and isoprene, the content ratio ofbutadiene is 0.5-99.5% by weight in general, preferably 195% by weight,more preferably 5-95% by weight, particularly preferably 5-90% byweight, while the content of isoprene is 0.5-99.5% by weight in general,preferably 5-99% by weight, more preferably 5-95% by weight,particularly preferably 10-95% by weight. In some cases, the contentratio of vinyl compound to be used is 0-99% by weight in general,preferably 0-95% by weight, more preferably 0-90% by weight.

When the above diene polymer (c) is a block copolymer, then thecomposition of the copolymer may be, for example,polystyrene/polybutadiene block copolymer,polystyrene/polybutadiene/polystyrene block copolymer (SBS),polystyrene/polyisoprene/polystyrene block copolymer (SIS), orpolyacrylonitril/polybutadiene block copolymer (NBR).

In these diene copolymers, furthermore, any partially hydrogenated dienecopolymers where parts of diene components are hydrogenated allow to beused. In each of these block copolymers, moreover, the structure of themolecule itself may be of any shape such as a linear, branched, orradial shape.

Among the polymers described above, the resin or rubber polymer to beused as the diene polymer (c) may be preferably one selected from thegroup of butadiene polymer, styrene/butadiene copolymer, isoprenepolymer, styrene/isoprene copolymer, and acrylonitrile/butadienecopolymer, and their partially hydride products.

The weight average molecular weight of the above diene polymer (c) is,though not limited in particular, preferably in a range where the dienepolymer (C) cannot be dissolved in organic solvents of low molecularweight, more preferably in the range of 1,000 to 5,000,000, particularlypreferable in the range of 5,000 to 500,000.

The terminal group of the above diene polymer (C) is not limited inparticular.

In the present invention I, it is important that the diene polymer (C)is in a solid form at the reaction temperature of the epoxidation. Thephrase “in a solid format the reaction temperature of the epoxidation”means that it is in the solid form such as powders or powder particlesat the reaction temperature of the epoxidation. In other words, it meansthat the diene polymer (C) is not in a liquid or paste form at thatreaction temperature.

The diene polymer (C) may be in the form of a commercially availablepellet if the ball-reduced particle size (hereinafter, simply referredto as a particle size) of the diene polymer (C) is in the rangedescribed above. For effectively performing the epoxidation reaction,the surface area of the diene polymer (C) may be increased by means ofcrushing. The method for crushing the diene polymer (C) may be anymethod using the typical crusher well known in the art. If the dienepolymer (C) is a rubber polymer, it is preferable to crush the polymerusing a freeze crush method.

More specifically, the particle size of the diene polymer (C) is in therange of 0.05 to 20 mm, preferably 0.07 to 20 mm, particularlypreferable 0.1 to 20 mm in average.

If the particle size of the diene polymer (C) is less than 0.05 mm, itbecomes difficult to manipulate the polymer, especially to perform asolid-liquid separation If the particle size of the diene polymer (C) islarger than 20 mm, then the surface area of the diene polymer (C)becomes small. Thus, the epoxidation reaction from the surface proceedsslowly, failing to achieve the characteristics of the present invention.

The term “ball-reduced particle size” is defined as a diameter of theball having the same volume as an average volume of the diene polymer(C).

The shape of the diene polymer (C) may be, but not limited to,spherical, cube, rectangular, cylindrical, prismatic, conical,semispherical, rugby ball, egg, cocoon, or the like, or any combinationthereof. In either shape, it is preferable that the average particlesize of the diene polymer (C) in terms of a ball is in the above range.

In the present invention II, it is important that the diene polymer (C)is dispersed and/or suspended in a reaction system of aqueous medium inthe presence of a phenol-based stabilizer and/or a phosphorus-basedstabilizer, where the ball-reduced particle size is in the same range asthat of the present invention I.

If the diene polymer (C) is dispersed or suspended at the reactiontemperature, it means that the diene polymer (C) is in the solid form ofpowders, particles, or the like. In addition, it means that the dienepolymer is not in the form of liquid- or paste-like powders orparticles, or any combination thereof to form any linked structure. Ifthe diene polymer is a liquid- or paste-like powder, these powdersbecome easy to coagulate with each other, so that it becomes difficultto stir the mixture.

In the present invention I, the medium (A) to be used is an inactivesolvent that does not substantially dissolve the diene polymer (C) ofthe present invention, including water, alcohol such as methanol orethanol, ketone such as acetone, linear aliphatic hydrocarbon such asnormal hexane, normal heptane, or normal octane, or the like. Amongthem, a preferable medium is water, methanol, or ethanol.

The powder particles (B) insoluble in the above medium (A) are inorganicparticles, organic/inorganic complex particles, or a mixture thereofhaving an average particle size of 0.1-100 ìm in general, preferably0.1-50 ìm. If the average particle size is larger than 100 ìm, theblocking-preventing effect can be decreased. Thus, it is not preferablebecause of the increase in the usage amount.

The inorganic particles include talc, silica, mica, diatomite, kaolin,barium sulfate, calcium carbonate, magnesium carbonate, magnesiumhydroxide, magnesium oxide, and so on. Preferable inorganic particlesare talc, silica, magnesium hydroxide, and magnesium oxide.

The organic/inorganic complex particles include colloidal silica orsol-gel processed silica as described in JP-A-09-194208, core/shellcomplex disclosed in JP-A-2001-98164, and so on.

The blending ratio of the medium (A), the insoluble powder particles(B), and the diene polymer (C) is 50-1000 parts by weight, preferably100-1000 parts by weight of the medium (A), and 0.01-5 parts by weight,preferably 0.05-3 parts by weight of the powder particles (B) withrespect to 100 parts by weight of the diene polymer (C).

If the usage amount of the medium (A) is less than 50 parts by weight,the diene polymer (C) cannot be sufficiently dispersed or suspended inthe medium (A). On the other hand, if it is more than 1000 parts byweight, the concentration of the epoxidation agent becomes low causingthe epoxidation reaction to take more time, so that it becomesinefficient.

The usage amount of the powder particles (B) is less than 0:01 parts byweight, the blocking between pellets is generated to form a block, sothat it becomes to difficult to remove it. On the other hand, if it ismore than 5 parts by weight, undesired powder particles are contaminatedinto drainage. Thus, the recovery method becomes complicated, so that itis not preferable.

In the process for producing the epoxidized diene polymer in accordancewith the present invention I, there are three steps. That is, the firststep is an epoxidation reaction where the diene polymer is epoxidizedwith a peroxide in the presence of powder particles in the medium (A) inwhich the diene polymer is insoluble, the second step is a washing step,or neutralization and washing steps, and the third step is one forremoving the solvent from the mixture.

In the method, preferably, an organic solvent is used as a reactionaccelerator in the first step.

In the second step, the polymer is subjected to the washing, or theneutralization and washing and is then separated by means of asolid-liquid separation, followed by supplying the polymer to the thirdstep. In the third step, subsequently, the polymer obtained from thesecond step is dried while keeping the form thereof, followed bycollecting the product as the desired epoxidized diene polymer.

The characteristics of the present invention I include the capability ofpreventing the blocking during the epoxidation reaction performed in adispersion system by the use of powder particles at the time ofepoxidation, as well as preventing the blocking of the product obtainedby the drying treatment. Furthermore, another characteristic feature isthat the gel content in the resulting epoxidized diene polymer is low,compared with the conventional one.

The reaction accelerators used in the epoxidation reaction, which differaccording to the type of the diene polymer (C) and the reactionconditions of the epoxidation, include linear and branched hydrocarbonssuch as hexane and octane, and their alkyl-substituted derivatives;alicyclic hydrocarbons such as cyclohexane and cycloheptane, and theiralkyl-substituted derivatives; aromatic hydrocarbons such as benzene,naphtalene, toluene, and xylene, and their alkyl substituted aromatichydrocarbons; aliphatic carboxylates such as methyl acetate, ethylacetate; halogenated hydrocarbons such as chloroform; and so on. Amongthem, from the points of capability of dissolving the peroxide as theepoxidizing agent, the solubility of the dine polymer (C) the facilityto collect the organic solvent after the epoxidation, and so on,cyclohexane (solubility parameter value, i.e., SP=8.2), ethyl acetate(SP=9.1), chloroform (SP=9.3), benzene (SP=9.2), toluene (SP=8.9),xylene (SP=8.8), hexane (SP=7.4), tetrahydrofuran (SP=9.1), and so onare preferable. Each of them may be used alone or they may be used as acombination of two or more thereof.

In addition, these organic solvents as the reaction accelerators can beselected depending on the type of the diene polymer (C). The organicsolvent has the function of infiltrating into the inside of the dienepolymer (C) in a solid state to transfer the agent into the inside ofthe diene polymer (C) and to epoxidize the inside of the dienepolymer(C). Thus, the criteria for selecting the organic solvent is one capableof dissolving or swelling the diene polymer (C), or being infiltratedinto the diene polymer (C) and having a solubility parameter value inthe range of 7.0 to 10. The organic solvent having a solubilityparameter value of over 10 shows insufficient abilities of dissolving orswelling the diene polymer (C), or being infiltrated into the dienepolymer (C), so that it cannot function as a desired reactionaccelerator. In addition, the organic solvent having a solubilityparameter value of less than 7.0 is similarly unpreferable.

As described above, the reaction accelerator is responsible fordissolving or swelling the diene polymer (C), or being infiltrated intothe diene polymer (C). Depending on the usage amount of the reactionaccelerator, therefore, there is a possibility that the reaction in anaqueous dispersion system, which is the characteristic feature of thepresent invention, cannot be progressed due to the generation ofblocking between the polymer particles. That is, the surface of thepellet becomes dissolved, so that the blocking between diene polymerscan occur. As a result, agitation becomes impossible and then theproduct becomes difficult to be collected from the reaction vessel.

The blending ratio of the reaction accelerator to the diene polymer (C)is appropriately selected according to the type of the diene polymer,the type of the reaction accelerator, the reaction temperature, and soon. In general, however, the reaction accelerator may be of 0.5-100parts by weight, preferably 0.5-75 parts by weight with respect to 100parts by weight of the diene polymer (C).

If the blending amount of the reaction accelerator is less than 0.5parts by weight, it means that the amount of the reaction accelerator tobe required to the reaction between the diene polymer (C) and theepoxidizing agent is insufficient. In this case, therefore, it isinefficient because the epoxidation reaction takes much time tocomplete. In addition, if the blending amount of the reactionaccelerator is over 100 parts by weight, the surface of pellet or powder(hereinafter, simply referred to as “pellet”, except in Examples) of thediene polymer (C) becomes dissolved, causing the blocking between thediene polymer pellets. In this case, it may become difficult to performdispersion by agitation during the epoxidation reaction. Thus, theepoxidation reaction in a dispersed state is liable to becomeimpossible. In addition, it becomes difficult to collect the epoxidizedproduct from the reaction vessel.

In the process for producing the epoxidized diene polymer in accordancewith the present invention II, the epoxidation reaction is performed inan aqueous medium. The epoxidizing agent is infiltrated into the insideof the dispersed particle of the diene polymer (C). Therefore, theorganic solvent described in the present invention I may be used as asolvent for accelerating the epoxidation reaction.

In the method of the present invention II, a phenol-based stabilizerand/or a phosphorus-based stabilizer for improving the heat stability ofthe epoxidized diene polymer product at the time of an epoxidationreaction is provided in a reaction system.

The typical examples of the phenol-based stabilizer includetetrakis(methylene-3-(3′,5′-di-tert-butyl-4′-hydroxyphenyl)propionate)methane,1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4′-hydroxybenzyl)benzene,2,6-di-tert-butyl-4-methylphenol,4-hydroxymethyl-2,6-di-tert-butylphenol,2,4-bis-(n-octylthio)-6-(4-hydroxy-3-5-di-tert-butylanilino)-1,3,5-triazine,octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,triethyleneglycol-bis(3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate),1,3,5-tris-(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate,2,2′-methylene-bis(4-methyl-6-tert-butylphenol),3,9-bis(2-(3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy)-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane,2,6-di-tert-butyl-4-ethylphenol, butylated hydroxyanisole,2,2′-dihydroxy-3,3′-dicyclohexyl-5,5′-dimethyl-diphenylmethane,1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane,4,4′-butylidene-bis-6-tert-butyl-m-cresol,bis(3-cyclohexyl-2-hydroxy-5-methylphenyl)methane,2,2′-methylene-bis-(4-ethyl-6-tert-butylphenol),1,1-methylene-bis-(2′-methyl-4′-hydroxy-5′-tert-butylphenyl)butane, andso on. These phenol-based stabilizers may be used as a combination oftwo or more thereof.

Also, the typical examples of the phosphorus-based stabilizer includetrisnonylphenyl phosphite, tris(2,4-di-tert-butylphenyl)phosphite,tris(2-tert-butylphenyl)phospite, tris(2,6-di-tert-butylphenyl)phospite,tris(2,4-bis(1,1-dimethylpropyl)phenyl)phosphite, and so on. Each ofthese phosphorus-based stabilizers may be used alone, or they may beused as a combination of two or more thereof.

The usage amount of the stabilizer may be 0.01-5 parts by weight,preferably 0.01-3 parts by weight, more preferably 0.05-5 parts byweight, still more preferably 0.1-5 parts by weight, particularlypreferably 0.1-2 parts by weight with respect to 100 parts by weight ofthe diene polymer (C). If the usage amount of the stabilizer is lessthan 0.01 parts by weight, the improved effects cannot be found in theheat stability and the tone of color. In addition, even if it is over 5parts by weight, effects beyond those obtainable in the presentinvention cannot be attained.

The stabilizer can be uniformly dispersed in the epoxidized dienepolymer (C) by adding the stabilizer at the time of epoxidationreaction. In addition, therefore, one of the operations, known as apost-addition to be performed at the time of extrusion becomesunnecessary.

The production method according to the present invention II includes thefollowing steps. That is, a first step of performing an epoxidationreaction of the diedine polymer with a peroxide in the presence of theheat stabilizer in the aqueous solvent, a second step being a washingstep, or being neutralization and washing steps, and optionally a thirdstep of removing a solvent if the first step uses an organic solvent asa reaction accelerator. In the second step, the polymer that has beensubjected to the washing step or the neutralization and washing steps isseparated through a solid-liquid separation. In the third step,subsequently, the polymer obtained from the second step is dried whilekeeping the form thereof, and/or is dried using a mixing vaporizer,thereby recovering the product as the desired epoxidized diene polymer.

One of the characteristics of the present invention II is an excellentheat stability of the epoxidized diene polymer obtained by using theheat stabilizer at the time of epoxidation and uniformly infiltrating itinto the diene polymer.

The reaction-accelerating solvent, which can be used for the epoxidationof diene polymer (C) in a state of being dispersed and/or suspended, maybe preferably a solvent capable of dissolving or swelling the dienepolymer (C), or being infiltrated into the diene polymer under theepoxidation conditions. The selection of an appropriate organic solventdiffers depending on the type of the diene polymer (C), the reactionconditions of the epoxidation, and so on. Examples of the usable organicsolvents include those described in the present invention I.

In addition, these organic solvents are chosen according to the dienepolymer targeted for epoxidation. The organic solvent has the functionsof dissolving a peroxide (epoxidizing agent) and a heat stabilizer, orinfiltrating into the inside of the diene polymer in a solid state totransfer these agents into the inside of the diene polymer (C) and tofix these agents in the diene polymer (C). Thus, the criteria forselecting the organic solvent is preferably to select one capable ofdissolving or swelling the diene polymer (C), or being infiltrated intothe diene polymer (C), and having a solubility parameter value of 10 orless. The organic solvent having a solubility parameter value of over 10shows insufficient abilities of dissolving or swelling the diene polymer(C), or being infiltrated into the diene polymer (C), so that it cannotfunction as the desired reaction accelerator. In the case of using theorganic solvent as a reaction-accelerating solvent, the organic solventmay be 0.5-100 parts by weight, preferably 0.5-75 parts by weight withrespect to 100 parts by weight of the diene polymer (C). Water may be50-1000 parts by weight, preferably 100-1000 parts by weight withrespect to 100 parts by weight of the diene polymer (C). Furthermore,the amount of water to be used is almost the same even in the absence ofthe organic solvent.

The reaction-accelerating solvent described above dissolves or swellsthe diene polymer (C), or is infiltrated into the diene polymer.Depending on the usage amount of the reaction accelerator, therefore,there is a possibility that the reaction in an aqueous dispersionsystem, which is the characteristic feature of the present invention,cannot be progressed due to generation of blocking between the polymerparticles. For preventing the blocking between the polymer particles andproceeding the reaction, the powder particles described in the inventionI can be used at the addition ratio described in the invention I.

The peroxide to be used as an epoxidizing agent in the presentinventions I and II may be a percarboxylic acid compound such asperformic acid, peracetic acid, and perpropionic acid. In addition, theepoxidation can be performed also in a system using the above peroxideincluding water, which was induced from hydrogen peroxide.

Among these peroxides, peracetic acid is preferable because of itsability to proceed the epoxidation effectively. If one of thepercarboxylic acids is used as an epoxidizing agent, the percarboxylicacid is preferably dissolved in the solvent. Examples of the solventsfor the percarboxylic acids include hydrocarbons such as hexane, organicacid esters such as ethylacetate, and aromatic hydrocrabons such astoluene. These solvents have the same effects as those of the abovereaction accelerators with respect to the epoxidation reaction and arecapable of accelerating the epoxidation reaction by infiltrating to theinside of the diene compound (C) Thus, it is preferable to use thesesolvents.

In the system using a peroxide induced from hydrogen peroxide, there aretwo methods of performing epoxidation. In one of these methods, hydrogenperoxide is previously reacted with a lower carboxylic acid such asformic acid, acetic acid, propionic acid, butyric acid, and isobutyricacid, to produce a percarboxylic acid. Then, the resulting percarboxylicacid is added as an epoxidizing agent in the reaction system to therebyperform epoxidation. In the other method, an epoxidation is performedusing hydrogen peroxide in the presence of a catalyst such as osmiumsalt and tungstic acid and a solvent. The solvents which can be used inthis case are those listed in the above description.

When the epoxidation is performed by a production method according toeither the present inventions I or II, the oxirane oxygen concentrationof an epoxidized compound to be obtained can be adjusted by changing thereaction molar ratio of the epoxidizing agent and the amount of doublebonds in the diene polymer (C).

This reaction molar ratio varies depending on the oxirane oxygeneconcentration of the epoxidized compound to be obtained. The reactionmolar ratio of the amount of double bonds in the organic polymertargeted for epoxidation and the sheer amount of peroxide can bepreferably selected from the range of 1.0 to 3.0, preferably from 1.1 to2.5.

The oxirane oxygen concentration of the epoxidized diene polymer to beobtained by adjusting the reaction molar ratio to be within the aboverange can be adjusted to 0.3-5.0% by weight, preferably 0.3-4.5% byweight.

The reaction temperature at the time of epoxidizing the diene compound(C) in accordance with a production method according to the presentinvention I or II varies depending on the type of diene polymer (C), thedegree of surface area, the type of the solvent, the type and thequantity of the epoxidizing agent, and the reaction time. However, itcan be selected within the range of 10-70° C. If the reactiontemperature is less than 10° C., the reaction rate becomes slow and thusnot suitable for practical use. If the reaction temperature is over 70°C., it is not preferable because self-decomposition of the peroxidebecomes extreme. Furthermore, there is a problem in that the blocking isgenerated as the surface of the diene polymer (C) is dissolved using theorganic solvent. A particularly preferable reaction temperature is inthe range of 30 to 60° C.

The reaction pressure for the epoxidation is typically an atmosphericpressure, or it may be a slightly reduced or slightly increased pressuretherefrom.

The reaction time for the epoxidation of diene polymer (C) in aproduction method in accordance with the present invention I or IIvaries according to the type of diene polymer (C), the degree of surfacearea, the type of the solvent, the type and quantity of the epoxidizingagent, and the reaction temperature. In general, however, it can beselected within the range of 1 to 24 hours. If the reaction time is lessthan 1 hour, the conversion rate of the double bond is too small for thepractical use. On the other hand, if the reaction time is over 24 hours,for example in the case of using peroxide acid, a side reaction of thediene polymer is generated. Such a side effect is not preferable becauseit becomes one of causes for the decrease in the yield of the epoxidizeddiene polymer.

In a production method according to the present invention I, thereaction solution after the epoxidation reaction is in a state in whichan epoxidized diene polymer as a product is dispersed or suspended inthe medium (A) while keeping its solid state, and it is obtained as asuspension solution in which the organic solvent and carboxylic acid aredissolved in the medium (A). Separation and recovery of the epoxidizedcompound as a product in a solid form may be performed by filtration,centrifugation, or the like. The separated and recovered epoxidizedcompound as a product in a solid form is washed with water to remove themedium (A), the organic solvent, the carboxylic acid, and the like,which are attached on the surface thereof.

It is preferable to shift to the next step, i.e., a solvent-removingstep, after addition of a heat stabilizer to the solid-form polymerseparated by the above method. Such addition of a heat stabilizer iseffective to prevent the polymer from degradation due to oxidation andfrom thermal degradation at the time of removing the organic solvent inthe next step. They may be directly added into the product in a solidform, or dissolved in a hydrocarbon solvent before added.

The heat stabilizer which can be used may be a phenol-based stabilizer,a phosphorus-based stabilizer, or the like, which are known in the artand are described in the invention II. The stabilizer may be added inthe reaction system during the epoxidation step. The usage amount of thestabilizer is just the same as in the case of the present invention II.

According to the production method of the invention II, the reactionsolution after the epoxidation is in a state in which the epoxidizeddiene copolymer as a product is being dispersed or suspended as a solidform in an aqueous medium and is also obtained as a suspension in whichan organic solvent and carboxylic acid are dissolved in the solvent. Forseparating and recovering the epoxidized compound of a solid-formproduct from the suspension, filtration, centrifugation, or the like canbe used. The separated and recovered epoxidized compound of a solid-formproduct is washed with water to remove the solvent, carboxylic acid, orthe like from the surface thereof. Subsequently, if it is required,neutralization and washing are performed. An alkali solution to be usedfor the neutralization may be a solution of lithium hydroxide, sodiumhydroxide, potassium hydroxide, calcium hydroxide, lithium carbonate,sodium carbonate, potassium carbonate, calcium carbonate, sodiumbicarbonate, potassium bicarbonate, sodium acetate, potassium acetate,aqueous ammonia, or the like.

In the method of the inventions I and II, subsequently, the productobtained is dried and is then provided as a product. Here, the term“dry” means that the obtained polymer may be dried by means ofdesolvation using an indirect heating method such as a steam strippingmethod, followed by the removal of water or the like by direct heating,and the medium (A) and the organic solvent are directly removed from theobtained polymer using at least one drier selected from a vacuum dryer,a hot air dryer, a mixing-type extruder, and the like, so that the watercontent of the polymer can be less than 1% by weight.

In the present inventions I and II, various kinds of additives can beadded to the polymer depending on the purpose. For example, there aregiven a softener such as oil, a plasticizer, an antistat, a lubricant, aultraviolet absorber, a fire retardant, a pigment, an inorganic filler,an organic or inorganic fiber, a reinforcing agent such as a carbonblack, and other thermoplastic resins. Incidentally, these additives maybe preferably added before introducing to the drying step.

The surface layer of the epoxidized diene polymer particles in the formof a pellet or the like obtained by the invention I or II allows 0.01-5%by weight of inorganic materials to attach with respect to the wholeparticles. In addition, the center part of the epoxidized diene polymerparticles may include unreacted diene polymer that is not reacted in theepoxidation.

In the epoxidized diene polymer obtained by the method of the presentinventions I or II, especially of the present invention II, it ispreferable that the gel content is 2% or less by weight or less, morepreferably 0.2% or less by weight because the external appearance (i.e.,the surface condition) of the final product using the epoxy dienepolymer becomes excellent.

In addition, as a measure of the heat resistance of the epoxidized dienepolymer, it is desirable that a gel content after heating underpredetermined conditions is less than 2.5 times, more preferably lessthan 0-2 times the original gel content. If the gel content is withinthis limited range, the heat stability of the product can be improved.In addition, after the same heating, a strand is formed by the extruder,and the visual observation is made on the surface of the strand. As aresult, no alien substance is found, and this means that the polymer hasgood heat stability.

EXAMPLES

The present invention will next be described more in detail by way ofexamples. However, the present invention is not limited only to theexamples described hereunder, so long as the scope of the invention isnot surpassed.

In the following description, “parts” and “%” are all based on a weightbasis.

Various measurements were performed using the following methods,respectively.

(1) Oxygen Concentration of Oxirane:

The oxygen concentration of oxirane of the epoxidized diene polymer ismeasured in accordance with ASTM-1652.

(2) Gel Content:

0.1 g of the dried epoxidized diene (co)polymer was added in 10 ml oftoluene and the mixture was stirred at 25° C. for 3 hours to dissolvethe polymer in the toluene. Subsequently, the mixture solution waspoured onto a wire mesh (200 mesh sieve). An insoluble matter that wastrapped on the wire mesh was dried for 2 hours at 120° C., followed bymeasuring the weight of the dried product (i.e., the dried epoxidizeddiene polymer). The resulting weight of the product is expressed in % byweight.

(3) Gel Content After the Application of Heat:

The dried epoxidized diene (co)polymer was left in an oven at 180° C.for 30 minutes (in the air). Then, the content of the solvent-insolublematter was measured. The measuring result was used as one of measures ofthe heat stability. If the gel content after the application of heat isless than 2.5 times the gel content before the application of heat, theheat stability is assumed to be almost favorable.

(4) The Surface Condition of the Epoxidized Diene (Co)Polymer After theApplication of Heat:

A pellet, which had been heated under the same heating condition as thatof the above item (3), was used. The pellet was forced through a meltindexer (a heat temperature of 180° C., a heat-melting time of 5minutes, a load of 5 kg, and a die diameter of 1 mm) to provide a linearstrand of about 1 mm in diameter, followed by making a visualexamination of the surface of the resulting strand. The results weresymbolized (“O”: smooth surface; and “X”: grain like surface).

(5) Ball-reduced Particle Size (Also Referred to as “Ball-reducedAverage Particle Size”):

The volume of the dried diene (co)polymer particles (dry weight: 5 g)targeted for epoxidation was evaluated by measuring the weight thereofin distilled water, followed by calculating an average volume perparticle from that volume. Then, the diameter of a ball having the samevolume as the average volume of the particle was calculated and was thenprovided as ball-reduced particle size or a ball-reduced averageparticle size.

In the examples and the comparative examples, the same agents and thesame instrument were used as follows.

Four-necked flask (capacity: 3 liters): equipped with a stirrer,thermometer, dropping funnel, and reflux condenser, and served as areaction vessel for an epoxidizing reaction.

Talc: Talc MWHS-T (average particle size: 2.7 ìm), manufactured byHayashi Kasei Co., Ltd., JAPAN

Stabilizer: Irganox 1010 (trade name), manufactured by Chiba SpecialtyChemicals, Co., Ltd., and phenolic heat stabilizer.

First, we will describe the examples of the present invention I.

Example I-1

In a four-necked flask were placed 300 g of a block-copolymer ofpolystyrene-polybutadiene-polystyrene (SBS) (trade name: TR2000, aball-reduced average particle size of 3.5 mm, manufactured by JapanSynthetic Rubber Co., Ltd.), 600 g of water, and 0.6 g of talc, and thecontents were stirred and thoroughly mixed so as to disperse SBS. Theinside of the flask was heated to 40° C., and 100 g of 30% ethyl acetate(SP=8.9) solution of peracetic acid was continuously added dropwise tothe flask, the mixture being stirred for epoxidation for 5 hours at 40°C.

In each of the examples in the present inventions I and II, withoutexceptions, the reaction proceeded without causing any blocking betweenthe pellets. After completion of the reaction, solid matter wasrecovered from the reaction solution by filtration and was then washedwith deionized water.

Subsequently, as a post treatment (1), the recovered solid matter wasdried under reduced pressure at 120° C. to remove water and theremaining solvent from the solid matter, resulting in 302 g ofepoxidized SBS. The obtained epoxidized SBS had 0.2% by weight oftoluene-insoluble matter and an oxirane oxygen concentration of 1.5% inthe dissolved portion except the surface layer.

On the other hand, as a post treatment (2), the recovered solid matterwas subjected to a kneading-type evaporator to remove water and theremaining solvent from the solid matter, resulting in 300 g ofepoxidized SBS. The obtained epoxidized SBS had the toluene-insolublematter in an amount of 0.03% by weight and an oxirane oxygenconcentration of 1.5% by weight in the dissolved portion except thesurface layer.

Example I-2

In a four-necked flask were placed 300 g of SBS (TR2000) as that used inExample I-1, 600 g of water, and 1.5 g of talc, and the contents werestirred and thoroughly mixed so as to disperse SBS. The inside of theflask was heated to 40° C., and 168 g of 30% ethyl acetate solution ofperacetic acid was continuously added dropwise to the flask, the mixturebeing stirred for epoxidation for 4 hours at 40° C. After completion ofthe reaction, the reaction solution was processed in the same manner asin Example I-1.

In the post treatment (1), 300 g of epoxidized SBS was obtained. Theobtained epoxidized SBS had 0.4% by weight of toluene-insoluble matterand an oxirane oxygen concentration of 2.3% by weight in the dissolvedportion except the surface layer.

In the post treatment (2), the resulting epoxidized SBS had thetoluene-insoluble matter in an amount of 0.05% by weight and an oxiraneoxygen concentration of 2.3% by weight in the dissolved portion exceptthe surface layer.

Example I-3

In a four-necked flask were placed 300 g of a copolymer ofpolystyrene-polybutadiene-polystyrene (SBS) (trade name: Tafprene 125, aball-reduced average particle size of 3.0 mm, manufactured by AsahiKasei Corp.), 600 g of water, and 1.5 g of talc, and the contents werestirred and thoroughly mixed so as to disperse SBS. The inside of theflask was heated to 40° C., and 168 g of 30% ethyl acetate solution ofperacetic acid was continuously added dropwise to the flask, the mixturebeing stirred for epoxidation for 4 hours at 40° C. After completion ofthe reaction, the reaction solution was processed in the same manner asin Example I-1.

In the post treatment (1), 300 g of epoxidized SBS was obtained. Theobtained epoxidized SBS had 0.4% by weight of toluene-insoluble matterand an oxirane oxygen concentration of 2.3% by weight in the dissolvedportion except the surface layer.

In the post treatment (2), the resulting epoxidized SBS had thetoluene-insoluble matter in an amount of 0.02% by weight and an oxiraneoxygen concentration of 2.3% by weight in the dissolved portion exceptthe surface layer.

Example I-4

In a four-necked flask were placed 300 g of SBS (TR2000) used in ExampleI-1, 700 g of water, and 6 g of talc, and the contents were stirred andthoroughly mixed so as to disperse SBS. The inside of the flask washeated to 40° C., and 250 g of 30% ethyl acetate solution of peraceticacid was continuously added dropwise to the flask, the mixture beingstirred for epoxidation for 5 hours at 40° C. After completion of thereaction, the reaction solution was processed in the same manner as inExample I-1.

In the post treatment (1), 300 g of epoxidized SBS was obtained. Theobtained epoxidized SBS had 0.9% by weight of toluene-insoluble matterand an oxirane oxygen concentration of 3.0% by weight in the dissolvedportion except the surface layer.

In the post treatment (2), the resulting epoxidized SBS had thetoluene-insoluble matter in an amount of 0.2% by weight and an oxiraneoxygen concentration of 3.0% by weight in the dissolved portion exceptthe surface layer.

Example I-5

In a four-necked flask were placed 300 g of a copolymer ofpolystyrene-polybutadiene-polystyrene (SBS) (trade name: As a flex 810,a ball-reduced average particle size of 3.8 mm, manufactured by AsahiKasei Corp.), 600 g of water, and 1.5 g of talc, and the contents werestirred and thoroughly mixed so as to disperse SBS. The inside of theflask was heated to 40° C., and 150 g of 30% ethyl acetate solution ofperacetic acid was continuously added dropwise to the flask, the mixturebeing stirred for epoxidation for 4 hours at 40° C. After completion ofthe reaction, the reaction solution was processed in the same manner asin Example I-1.

In the post treatment (1), 300 g of epoxidized SBS was obtained. Theobtained epoxidized SBS had 0.8% by weight of toluene-insoluble matterand an oxirane oxygen concentration of 1.7% by weight in the dissolvedportion except the surface layer.

In the post treatment (2), furthermore, the recovered solid matter wassubjected to the kneading-type evaporator under reduced pressure at 200°C. to remove water and the remaining solvent from the solid matter,resulting in obtaining 300 g of epoxidized SBS. The obtained epoxidizedSBS had the toluene-insoluble matter in an amount of 0.2% by weight andan oxirane oxygen concentration of 1.7% by weight in the dissolvedportion except the surface layer.

Example I-6

In a four-necked flask were placed 300 g of a block-copolymer ofpolystyrene-polyisoprene-polystyrene (SIS) (tradename: Clayton D1117, aball-reduced average particle size of 3.9 mm, manufactured by ShellChemicals Ltd.), 600 g of water, and 0.6 g of talc, and the contentswere stirred and thoroughly mixed so as to disperse SIS. The inside ofthe flask was heated to 40° C., and 164 g of 30% ethyl acetate solutionof peracetic acid was continuously added dropwise to the flask, themixture being epoxidized for 3 hours at 40° C. After completion of thereaction, the reaction solution was processed in the same manner as inExample I-1.

In the post treatment (1), 302 g of epoxidized SIS was obtained. Theobtained epoxidized SIS had 1.5% by weight of toluene-insoluble matterand an oxirane oxygen concentration of 2.2% by weight in the dissolvedportion except the surface layer.

In the post treatment (2), the resulting epoxidized SIS had thetoluene-insoluble matter in an amount of 1.3% by weight and an oxiraneoxygen concentration of 2.2% by weight in the dissolved portion exceptthe surface layer.

Example I-7

In a four-necked flask were placed 300 g ofpolyacrylonitrile-polybutadiene (NBR) (trade name: Nippol NBR. DN 214, aball-reduced average particle size of 3.4 mm, manufactured by NipponZeon Co. Ltd.), 600 g of water, and 1.5 g of talc, and the contents werestirred and thoroughly mixed so as to disperse NBR. The inside of theflask was heated to 40° C., and 100 g of 30% ethyl acetate solution ofperacetic acid was continuously added dropwise to the flask, the mixturebeing epoxidized for 6 hours at 40° C. After completion of the reaction,solid matter was recovered from the reaction solution by filtration andwas then washed with deionized water.

From the recovered solid matter, water and the remaining solvent wereremoved under reduced pressure to obtain 299 g of epoxidized NBR. Theobtained epoxidized NBR had the toluene-insoluble matter in an amount of1.2% by weight and an oxirane oxygen concentration of 1.5% by weight inthe dissolved portion except the surface layer.

Comparative Examples I-1 to I-5

The comparative Examples I-1, I-2, I-3, I-4, and I-5 were performed byalmost the same ways as those of Examples I-1, I-2, I-3, I-4, and I-5,respectively, except that powder particles of talk were not used.Consequently, in each of these Comparative Examples, the pellets wereadhered with each other just after the addition of the epoxidizingagent, so that the agitation had become difficult and the reaction haddiscontinued. In this case, furthermore, the contents could not berecovered from the flask.

According to the present invention I, significantly improved propertieswere exhibited by the addition of powder particles to the target organicpolymer at the time of epoxidation. That is, it becomes possible tosolve the problems of the prior art in which the blocking is occurred inresulting product, the product becomes difficult to be handled, and theworkability becomes substantially worse. In addition, there is provideda specific method that utilizes the above powder particles at the timeof epoxidation. Therefore, the method has the advantage of preventingthe blocking between the particulate substances, using the powderparticles as a particulate material for modifying other resins, or thelike, substantially reducing the amount of solvent insoluble matter inthe powder particles, and effecting a uniform dispersion with otherresin without causing any trouble.

Next, we will describe the examples of the present invention II.

Example II-1

In a four-necked flask were placed 300 g of SBS (TR2000) used in ExampleI-1, 600 g of water, 1.5 g of stabilizer (Irganox 1010 (Trade name)),and 0.6 g of talc, and the contents were stirred and thoroughly mixed soas to disperse SBS. The inside of the flask was heated to 40° C., and100 g of 30% ethyl acetate solution of peracetic acid was continuouslyadded dropwise to the flask, the mixture being stirred for epoxidationfor 5 hours at 40° C.

After completion of the reaction, solid matter was recovered from thereaction solution by filtration and was then washed with deionizedwater.

From the recovered solid matter, water and the remaining solvent wereremoved using a vented kneading extruder to obtain 302 g of epoxidizedSBS.

The obtained epoxidized SBS hadagel content of 0.02% by weight and anoxirane oxygen concentration of 1.5% by weight. In addition, a gelcontent after the application of heat was 0.04% by weight and thesurface of strands obtained by extruding pellets of the obtainedepoxidized SBS was smooth (“O”).

Example II-2

In a four-necked flask were placed 300 g of SBS (Tafprene 125) used inExample I-3, 600 g of water, 1.5 g of stabilizer (Irganox 1010 (Tradename)), and 0.6 g of talc, and the contents were stirred and thoroughlymixed so as to disperse SBS. The inside of the flask was heated to 40°C., and 100 g of 30% ethyl acetate solution of peracetic acid wascontinuously added dropwise to the flask, the mixture being stirred forepoxidation for 6 hours at 40° C. After completion of the reaction, thereaction solution was processed in the same manner as in Example II-1 toobtain 300 g of epoxidized SBS.

The obtained epoxidized SBS had a gel content of 0.02% by weight and anoxirane oxygen concentration of 1.5% by weight. In addition, a gelcontent after the application of heat was 0.04% by weight and thesurface of strands obtained by extruding pellets of the obtainedepoxidized SBS was smooth (“O”).

Example II-3

In a four-necked flask were placed 300 g of SBS (Tafprene 125) used inExample I-3, 600 g of water, 3.0 g of stabilizer (Irganox 1010 (Tradename)), and 0.6 g of talc, and the contents were stirred and thoroughlymixed so as to disperse SBS. The inside of the flask was heated to 40°C., and 10 g of 30% ethyl acetate solution of peracetic acid wascontinuously added dropwise to the flask, the mixture being stirred forepoxidation for 5 hours at 40° C. After completion of the reaction, thereaction solution was processed in the same manner as in Example II-1 toobtain 300 g of epoxidized SBS.

The obtained epoxidized SBS had a gel content of 0.02% by weight and anoxirane oxygen concentration of 1.5% by weight. In addition, a gelcontent after the application of heat was 0.02% by weight and thesurface of strands obtained by extruding pellets of the obtainedepoxidized SBS was smooth (“O”).

Example II-4

In a four-necked flask were placed 300 g of SBS (TR2000) used in ExampleI-1, 600 g of water, 3.0 g of stabilizer (Irganox 1010 (Trade name)),and 0.6 g of talc, and the contents were stirred and thoroughly mixed soas to disperse SBS. The inside of the flask was heated to 40° C., and100 g of 30% ethyl acetate solution of peracetic acid was continuouslyadded dropwise to the flask, the mixture being stirred for epoxidationfor 5 hours at 40° C. After completion of the reaction, the reactionsolution was processed in the same manner as in Example II-1 to obtain300 g of epoxidized SBS.

The obtained epoxidized SBS had a gel content of 0.02% by weight and anoxirane oxygen concentration of 1.5% by weight. In addition, a gelcontent after the application of heat was 0.02% by weight and thesurface of strands obtained by extruding pellets of the obtainedepoxidized SBS was smooth (“O”).

Example II-5

In a four-necked flask were placed 300 g of SBS (Tufprene125) 600 g ofwater, and 0.9 g of stabilizer (Irganox 1010 (Trade name)) and thecontents were stirred and thoroughly mixed so as to disperse SBS. Theinside of the flask was heated to 40° C., and 25 g of 30% ethyl acetatesolution of peracetic acid was continuously added dropwise, the mixturebeing stirred for epoxidation for 6 hours at 40° C. After completion ofthe reaction, the reaction solution was processed in the same manner asin Example II-1 to obtain 301 g of epoxidized SBS. The obtainedepoxidized SBS had a gel content of 0.01% by weight and an oxiraneoxygen concentration of 0.35% by weight. In addition, a gel contentafter the application of heat was 0.01% by weight and the surface ofstrands obtained by extruding pellets of the obtained epoxidized SBS wassmooth (1101).

Comparative Example II-1

In this example, 300 g of epoxidized SBS was obtained by the samereaction and recovery steps as those of Example II-1, except that noheat stabilizer was used. The obtained epoxidized SBS had a gel contentof 0.10% by weight and an oxirane oxygen concentration of 1.5% byweight. In addition, a gel content after the application of heat was1.0% by weight and the surface of strands obtained by extruding pelletsof the obtained epoxidized SBS was grainlike (X)

Comparative Example II-2

In this example, 300 g of epoxidized SBS was obtained by the samereaction and recovery steps as those of Example II-2, except that noheat stabilizer was used. The obtained epoxidized SBS had a gel contentof 0.12% by weight and an oxirane oxygen concentration of 1.5% byweight. In addition, a gel content after the application of heat was0.35% by weight and the surface of strands obtained by extruding pelletsof the obtained epoxidized SBS was grainlike (X).

According to the present invention II, therefore, there is provided amethod for cost-effectively producing an epoxidized polymer having alower amount of gel generated by the application of heat and anexcellent heat stability, where the pellet raw material can beepoxidized directly, the stabilizer can be included in it while there isno need to mix the stabilizer or the like in it by means of kneading, inaddition to the decrease in the energy cost for the dissolution in thesolvent and recovery of the product from the solvent, and so on,compared with the conventional method where the raw material is servedas an organic solution to be epoxidized.

Accordingly, the epoxidized diene polymers obtained according to thepresent inventions I and II can be used to form various molded products,such as sheets, films, injection molded products having various shapes,and blow-molded products, in addition to be used as: modifying agentsfor various kinds of thermoplastic resins and rubbers; adhesivecompounds; raw materials for adhesives; asphalt modifiers; and as rawmaterials for household electronic appliances, automobile parts,industrial parts, household articles, and toys, and so on.

1. A process for producing an epoxidized diene polymer, comprising:dispersing or suspending a diene polymer (C) in a medium (A) in thepresence of powder particles (B) insoluble in the medium (A), whereinthe diene polymer has a ball-reduced particle size in the range of 0.05to 20 mm; and epoxidizing a double bond of the diene polymer (C) by anepoxidizing agent in the presence of an optionally added phenol-basedstabilizer and/or an optionally added phosphorus-based stabilizer.
 2. Aprocess for producing an epoxidized diene polymer, comprising:dispersing or suspending a diene polymer (C) in an aqueous medium in thepresence of a phenol-based stabilizer and/or an phosphorus-basedstabilizer, wherein the diene polymer has a ball-reduced particle sizein the range of 0.05 to 20 mm; and epoxidizing the diene polymer (C) byan epoxidizing agent in the presence of powder particles (B) insolublein a medium that is optionally added.
 3. A process for producing anepoxidized diene polymer according to claim 1, wherein the medium (A) isan inert medium which does not dissolve the diene polymer.
 4. A processfor producing an epoxidized diene polymer as claimed in claim 3, whereinthe medium (A) is water.
 5. A process for producing an epoxidized dienepolymer as claimed in claim 1, wherein the powder particles (B) areinorganic particles and/or organic-inorganic complex particles.
 6. Aprocess for producing an epoxidized diene polymer as claimed in claim 5,wherein the inorganic particles are talc and/or silica.
 7. A process forproducing an epoxidized diene polymer as claimed in claim 1, wherein thetotal usage amount of the phenol-based stabilizer and/orphosphorus-based stabilizer is 0.05-5 parts by weight with respect to100 parts by weight of the diene polymer.
 8. A process for producing anepoxidized diene polymer as claimed in claim 1, wherein the dienepolymer (C) is at least one selected from the group consisting of:butadiene polymer, styrene/butadiene copolymer, isoprene polymer,styrene/isoprene copolymer, acrylonitrile/butadiene copolymer, andpartial hydrides thereof.
 9. A process for producing an epoxidized dienepolymer as claimed in claim 1, wherein the epoxidizing agent isperacetic acid, or the other percarboxylic acid which can be inducedusing hydrogen peroxide.
 10. A process for producing an epoxidized dienepolymer as claimed in claim 1, wherein a solvent for accelerating anepoxidizing reaction is used at the time of the epoxidizing reaction.11. A process for producing an epoxidized diene polymer as claimed inclaim 10, wherein the solvent for accelerating the epoxidizing reactionis an organic solvent having an SP (solubility parameter) value of 10 orless.
 12. A process for producing an epoxidized diene polymer as claimedin claim 11, wherein the solvent for accelerating the epoxidizingreaction is at least one selected from the group consisting of:cyclohexane, toluene, xylene, ethyl acetate; tetrahydrofuran, benzene,methyl ethyl ketone, and chloroform.
 13. A process for producing anepoxidized diene polymer as claimed in claim 1, wherein the epoxidizeddiene polymer has an oxirane oxygen concentration of 0.3-5.0% by weight.14. A process for producing an epoxidized diene polymer as claimed inclaim 1, wherein the epoxidizing reaction of the diene polymer isperformed at a temperature of 10-70° C.
 15. A process for producing anepoxidized diene polymer as claimed in claim 1, comprising: a first stepin which the diene polymer (C) dispersed or suspended in medium (A) isepoxidized in the presence of an epoxidizing agent and the powderparticle (B) or in the presence of an epoxidizing agent, a solvent foraccelerating an epoxidizing reaction, and the powder particle (B); asecond step in which the epoxidized diene polymer is washed with water,or the epoxidized diene polymer is neutralized and washed with water;and a third step in which the solvent for accelerating the epoxidizingreaction used in the first step is removed, where the third step is anoptional step to be provided as necessary.
 16. A process for producingan epoxidized diene polymer as claimed in claim 15, wherein the secondstep further includes an operation for a solid-liquid separation toseparate the epoxidized diene polymer that is to be supplied to thethird step.
 17. A process for producing an epoxidized diene polymer asclaimed in claim 15, wherein the removal of the solvent in the thirdstep further includes drying the epoxidized diene polymer obtained fromthe second step, while keeping the particle form of the epoxidized dienepolymer.
 18. A process for producing an epoxidized diene polymer asclaimed in claim 17, wherein the removal of the solvent in the thirdstep is performed by a kneading-type evaporator.
 19. A process forproducing an epoxidized diene polymer as claimed in claim 1, wherein theresulting epoxidized diene polymer has a gel content of not more than 2%by weight.
 20. A process for producing an epoxidized diene polymer asclaimed in claim 1, wherein the gel content of the epoxidized dienepolymer after heating it in an oven for 30 minutes at a temperature of180° C. (in air) is less than 2.5 times of the gel content of theepoxidized diene polymer before the heating.